Physiological effects of hydrocarbons on phytoplankton

Abstract

The effect of hydrocarbons on phytoplankton has been studied using laboratory cultures of marine diatoms and flagellates. Low oil concentrations ,stimulate photosynthetic activities while high oil concentration« cause inhibition. The concentrations required for both stimulation and toxicity depend on the individual species. The toxic effects become more obvious after a few days due perhaps to the slow penetration of the oils. The toxicity levels are also affected by the presence of organic material in the medium.. Studies on the ultrastructure hasrshown an effect of the paraffin fraction on the cell wall although the external morphology was not affected. Assimilation of hydrocarbons by the diatoms has also been proved by using gas chromatography. The competition between two species in the presence and absence of oil has been studied to obtain an idea of the ecological importance of this form of pollution.